Star Lore

Triangulus Antarcticus

The Antarctic Triangle

Triangulus Antarcticus is a constellation shown on a celestial globe made in 1589 by Jacob Floris van Langren and Petrus Plancius, referring to a star formation observed in 1501 by Amerigo Vespucci.

Its location may have been misinterpreted.
Florentine merchant, explorer, and navigator Amerigo Vespucci was one of the first Europeans to observe the stars of the southern hemisphere. Vespucci took part in at least two voyages to South America. The second one, between 1501 and 1502 took him to the coast of Brazil.

During this voyage, Vespucci prepared a catalogue of southern stars for his patron, King Manuel I of Portugal. In a letter to Lorenzo Pietro di Medici, Vespucci wrote, "I observed many other very beautiful stars, the movements of which I have diligently noted down and have described beautifully with diagrams in a certain little book of mine treating of this my voyage. But at present this Most Serene King has it, which I hope he will restore to me."

Apparently, the King never returned Vespucci's diagrams and unfortunately, they seem to be lost.
Amerigo Vespucci; Wikipedia
In 1503, Lorenzo di Medici published his correspondence with Vespucci, which included the following observation:
Vespucci's observation was first shown in 1589 on a celestial globe manufactured by Dutch cartographers Jacob Floris van Langren and Petrus Plancius. (The globe also showed for the first time the Southern Cross and the Magellanic Clouds).

On the 1589 globe, as well as on a 1594 star map, Plancius placed Triangulus Antarcticus between Argo Navis and the celestial south pole - a position that is most likely a misinterpretation of Vespucci's account.

Today, it is most commonly believed that the stars observed by Vespucci were the stars that later became the constellation Triangulum Australe, introduced by Keyser and de Houtman in 1603.

But with Vespucci's original diagrams being lost in the vault of a Portugese king, we will never know for sure.

Sources: ascensionglossary.com, encyclopediavirginia.org, Ian Ridpath
Triangulus Antarcticus on Plancius' celestial globe
Source: Royal Museum Greenwitch

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